February 15, 2002
12:30 PM (EST)

News Release Number: STScI-2002-06

New Instrument Package to Expand Space Telescope's Vision

February 15, 2002: NASA's Servicing Mission 3B for the Hubble Space Telescope will give the orbiting observatory a new camera that will significantly increase Hubble's abilities and enable a broad array of new astronomical discoveries. The Advanced Camera for Surveys (ACS) covers twice the area, has twice the sharpness, and is up to five times more sensitive to light than Hubble's workhorse camera, the Wide Field and Planetary Camera 2. The servicing mission will begin on Feb. 28 with the launch of the space shuttle Columbia. The simulated image [above, right] depicts how the cosmos will look through the "eyes" of the ACS.

Q & A: Understanding the Discovery

1.
What do both simulated images show?

The images depict a distant massive cluster of galaxies. The picture at left shows the cluster through the "eyes" of the Wide Field and Planetary Camera 2 (WFPC2). The WFPC2's view depicts the galaxies in the cluster as faint smudges. But the Advanced Camera for Surveys (ACS) will be able to see more galaxies in much more detail [image at right], including several faint arc-like features produced when the light from more distant galaxies is bent and magnified by the cluster, an effect called gravitational lensing. The cluster is "observed" by the two instruments for the same length of time and through the same color filters.

2.
What will the Advanced Camera for Surveys hunt for?

The Advanced Camera for Surveys (ACS) will search for very young galaxies that existed less than a billion years after the Big Bang, the explosive birth of the universe. Hubble has provided intriguing clues to how galaxies form and evolve. The ACS's greater sensitivity and higher efficiency will allow astronomers to see objects and details that could never have been seen before. The camera, for example, will be able to spot galaxies that are several times fainter than those detected by the Wide Field and Planetary Camera 2 (WFPC2), providing more details about how matter combines to form galaxies. The ACS can detect radiation ranging from the ultraviolet portion of the spectrum, through visible light, to a portion of the spectrum known as the near infrared.

The ACS contains an instrument known as a coronagraph that will allow astronomers to block out small bright sources of light in order examine the details of structures around the light sources. The coronagraph may allow astronomers to search for warps and gaps in the disks of gas and dust surrounding nearby stars that may be early signs of planet formation. The coronagraph will also be very useful to astronomers who study quasars, powerful distant objects in the farthest reaches of the universe that are thought to be highly active black holes in the center of galaxies.

The ACS also will search for "direct evidence" of planets in nearby solar systems. Although planets have been detected around many stars, all of them have been inferred through the gravitational wobbles they impart to their stars, rather than detected through a direct image of the planets themselves.